Structural parts, especially large structural parts, have typically been made from an acrylonitrile/butadiene/styrene rubber (ABS). When weatherability is required, a laminate of ABS and a layer of acrylonitrile/styrene/acrylic resin (ASA) or an acrylic resin is used. These materials have only adequate weatherability, poor chemical resistance, and a high density, which is a disadvantage when used in applications such as, for example, co-extruded profiles; boat hulls and boat decks as well as boat engine covers, consoles, and hatches; indoor and outdoor whirlpool tubs or hot tubs; pick-up truck caps, and body parts for golf carts, all-terrain vehicles, lawn mowers and lawn tractors, and agricultural equipment.
European Patent Application 873,862 discloses co-extruded laminates comprising at least one layer of a graft copolymer made from a propylene polymer material onto which is graft polymerized acrylic and/or styrenic monomers, and at least one other layer comprising one or more polyolefin materials, which may include a high melt strength propylene polymer material. These laminates are characterized by better weather resistance, better chemical resistance, greater toughness, and better scratch and mar resistance than materials available at that time for making large thermoformed structural parts.
However, there is still a need for polymer materials having even greater melt strength that will produce thermoformed parts that have an even higher surface gloss after thermoforming than currently available materials.